Some people treat Stalin's writings in a doctrinaire manner, with the result that they cannot analyse and see what is correct and what is not correct -- and even what is correct they treat as a panacea and apply indiscriminately; inevitably they make mistakes. For instance, Stalin put forward a formula that in different revolutionary periods, the main blow should be so directed as to isolate the middle-of-the-road social and political forces of the time. This formula of Stalin's should be treated according to circumstances and from a critical, Marxist point of view. In certain circumstances it may be correct to isolate the middle forces, but it is not correct to isolate them under all circumstances. Our experience teaches us that the main blow of the revolution should be directed at the chief enemy to isolate him, while as for the middle forces, a policy of both uniting with them and struggling against them should be adopted, so that they are at least neutralized; and, as circumstances permit, efforts should be made to shift them from their position of neutrality to one of alliance with us, for the purpose of facilitating the development of the revolution. But there was a time -- the ten years of civil war from 1927 to 1936 -- when some of our comrades crudely applied this formula of Stalin's to China's revolution by turning their main attack on the middle forces, singling them out as the most dangerous enemy; the result was that, instead of isolating the real enemy, we isolated ourselves, and suffered losses to the advantage of the real enemy. In the light of this doctrinaire error, the Central Committee of the Communist Party of China, during the period of the anti-Japanese war, formulated a policy of "developing the progressive-forces, winning over the middle-of the-roaders, and isolating the die-hards" for the purpose of defeating the Japanese aggressors. The progressive forces in question consisted of the workers, peasants and revolutionary intellectuals led by, or open to the influence of, the Communist Party. The middle forces in question consisted of the national bourgeoisie, the democratic parties and groups, and democrats without party affiliation. The die-hards referred to were the comprador-feudal forces headed by Chiang Kai-shek, who were passive in resisting the Japanese and active in fighting the Communists. Experience, gained through practice, proved that this policy of the Communist Party suited the circumstances of China's revolution and was correct.

https://www.marxists.org/history/international/comintern/sino-soviet-split/cpc/hedp.htm